According to The Free Dictionary http://idioms.thefreedictionary.com/good+for+what+ails+you
this is a rural idiom meaning something is "able to cure any problem or illness. (Usually used to describe food or liquor.) Have a sip of this whiskey. It's good for what ails you. Sally's beef broth is good for what ails you."
Here is Zephyr Hill Farm's non-alcoholic, non-caloric version of things that are good for what ails you. Photographs by Jenny Lea, prose by Susan Lea.
So if you've got something that ails you, why don't you follow our animals' advice and try one of these "good for what ails you" remedies?